Processing technologies and devices structures for forming integrated circuits (ICs) using metal-oxide-semiconductor-field-effect-transistors (MOSFETs) are well known in the art. It is understood that the term “MOSFET” is also used for device structures that employ other materials than simple oxide dielectrics and/or other conductors than simple metals. This is well known in the art. Accordingly, as used herein the term “MOSFET” is intended to include all such variations. Any type of semiconductor may be used.
Ordinarily, integrated circuit (IC) technologies and associated device structures are developed with specific performance goals in mind, as for example but not intended to be limiting, breakdown voltage, frequency response or speed, power consumption, critical dimensions, device packing density, achievable integration level, included device types and functions, etc. The development of a set of design rules, device types and associated manufacturing process flows that are capable of meeting the predetermined performance goals is a complex and expensive task. Once developed, transferring such a family of design rules and process flows to manufacturing is a further very large expense. Thus, there is an ongoing need for improvements that allow the performance capabilities of a particular technology to be extended without corresponding changes in the process capabilities or design rules. Stated another way, it is desirable to be able to achieve higher performance levels merely by altering the mask set designs (using the same design rules) while still using the available process technologies and/or flows already established in manufacturing. This has great economic benefit since it can allow an existing manufacturing technology to be extended to new classes of integrated circuit (IC) functions than had previously been possible, without a corresponding large investment in developing and installing new manufacturing technology.
Consider, for example, the case of an existing base manufacturing technology suitable for forming complex, dense, high speed, high performance system-on-a-chip (SOC) MOSFET integrated circuits. Suppose that the source-drain breakdown voltage (BVdss) rating of this base technology is, for example, Vbd-1 volts. While useful for many types of applications where this BVdss is sufficient, this base technology is not suitable for applications that require larger values of BVdss, that is (Vbd-2)=(Vbd-1)+Δ, where Δ is significant compared to (Vbd-1). Accordingly, it is desirable to be able to provide improved breakdown voltages. It is further desirable that such improved breakdown voltages are obtained without having to introduce any substantial change in the manufacturing technology. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.